元组对象
********

PyTupleObject

   这个 "PyObject" 的子类型代表一个 Python 的元组对象。

PyTypeObject PyTuple_Type

   "PyTypeObject" 的实例代表一个 Python 元组类型，这与 Python 层面的
   "tuple" 是相同的对象。

int PyTuple_Check(PyObject *p)

   如果 *p* 是一个元组对象或者元组类型的子类型的实例，则返回真值。

int PyTuple_CheckExact(PyObject *p)

   如果 *p* 是一个元组对象，而不是一个元组子类型的实例，则返回真值。

PyObject* PyTuple_New(Py_ssize_t len)
    *Return value: New reference.*

   Return a new tuple object of size *len*, or "NULL" on failure.

PyObject* PyTuple_Pack(Py_ssize_t n, ...)
    *Return value: New reference.*

   Return a new tuple object of size *n*, or "NULL" on failure. The
   tuple values are initialized to the subsequent *n* C arguments
   pointing to Python objects. "PyTuple_Pack(2, a, b)" is equivalent
   to "Py_BuildValue("(OO)", a, b)".

Py_ssize_t PyTuple_Size(PyObject *p)

   Take a pointer to a tuple object, and return the size of that
   tuple.

Py_ssize_t PyTuple_GET_SIZE(PyObject *p)

   Return the size of the tuple *p*, which must be non-"NULL" and
   point to a tuple; no error checking is performed.

PyObject* PyTuple_GetItem(PyObject *p, Py_ssize_t pos)
    *Return value: Borrowed reference.*

   Return the object at position *pos* in the tuple pointed to by *p*.
   If *pos* is out of bounds, return "NULL" and set an "IndexError"
   exception.

PyObject* PyTuple_GET_ITEM(PyObject *p, Py_ssize_t pos)
    *Return value: Borrowed reference.*

   Like "PyTuple_GetItem()", but does no checking of its arguments.

PyObject* PyTuple_GetSlice(PyObject *p, Py_ssize_t low, Py_ssize_t high)
    *Return value: New reference.*

   Return the slice of the tuple pointed to by *p* between *low* and
   *high*, or "NULL" on failure.  This is the equivalent of the Python
   expression "p[low:high]".  Indexing from the end of the list is not
   supported.

int PyTuple_SetItem(PyObject *p, Py_ssize_t pos, PyObject *o)

   Insert a reference to object *o* at position *pos* of the tuple
   pointed to by *p*.  Return "0" on success.  If *pos* is out of
   bounds, return "-1" and set an "IndexError" exception.

   注解:

     This function "steals" a reference to *o* and discards a
     reference to an item already in the tuple at the affected
     position.

void PyTuple_SET_ITEM(PyObject *p, Py_ssize_t pos, PyObject *o)

   Like "PyTuple_SetItem()", but does no error checking, and should
   *only* be used to fill in brand new tuples.

   注解:

     This macro "steals" a reference to *o*, and, unlike
     "PyTuple_SetItem()", does *not* discard a reference to any item
     that is being replaced; any reference in the tuple at position
     *pos* will be leaked.

int _PyTuple_Resize(PyObject **p, Py_ssize_t newsize)

   Can be used to resize a tuple.  *newsize* will be the new length of
   the tuple. Because tuples are *supposed* to be immutable, this
   should only be used if there is only one reference to the object.
   Do *not* use this if the tuple may already be known to some other
   part of the code.  The tuple will always grow or shrink at the end.
   Think of this as destroying the old tuple and creating a new one,
   only more efficiently.  Returns "0" on success. Client code should
   never assume that the resulting value of "*p" will be the same as
   before calling this function. If the object referenced by "*p" is
   replaced, the original "*p" is destroyed.  On failure, returns "-1"
   and sets "*p" to "NULL", and raises "MemoryError" or "SystemError".


Struct Sequence Objects
***********************

Struct sequence objects are the C equivalent of "namedtuple()"
objects, i.e. a sequence whose items can also be accessed through
attributes. To create a struct sequence, you first have to create a
specific struct sequence type.

PyTypeObject* PyStructSequence_NewType(PyStructSequence_Desc *desc)
    *Return value: New reference.*

   Create a new struct sequence type from the data in *desc*,
   described below. Instances of the resulting type can be created
   with "PyStructSequence_New()".

void PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)

   Initializes a struct sequence type *type* from *desc* in place.

int PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)

   The same as "PyStructSequence_InitType", but returns "0" on success
   and "-1" on failure.

   3.4 新版功能.

PyStructSequence_Desc

   包含要创建的结构序列类型的元信息。

   +---------------------+--------------------------------+----------------------------------------+
   | 域                  | C 类型                         | 意义                                   |
   |=====================|================================|========================================|
   | "name"              | "const char *"                 | 结构序列类型的名称                     |
   +---------------------+--------------------------------+----------------------------------------+
   | "doc"               | "const char *"                 | pointer to docstring for the type or   |
   |                     |                                | "NULL" to omit                         |
   +---------------------+--------------------------------+----------------------------------------+
   | "fields"            | "PyStructSequence_Field *"     | pointer to "NULL"-terminated array     |
   |                     |                                | with field names of the new type       |
   +---------------------+--------------------------------+----------------------------------------+
   | "n_in_sequence"     | "int"                          | number of fields visible to the Python |
   |                     |                                | side (if used as tuple)                |
   +---------------------+--------------------------------+----------------------------------------+

PyStructSequence_Field

   Describes a field of a struct sequence. As a struct sequence is
   modeled as a tuple, all fields are typed as "PyObject*".  The index
   in the "fields" array of the "PyStructSequence_Desc" determines
   which field of the struct sequence is described.

   +-------------+--------------------+-------------------------------------------+
   | 域          | C 类型             | 意义                                      |
   |=============|====================|===========================================|
   | "name"      | "const char *"     | name for the field or "NULL" to end the   |
   |             |                    | list of named fields, set to              |
   |             |                    | "PyStructSequence_UnnamedField" to leave  |
   |             |                    | unnamed                                   |
   +-------------+--------------------+-------------------------------------------+
   | "doc"       | "const char *"     | field docstring or "NULL" to omit         |
   +-------------+--------------------+-------------------------------------------+

const char * const PyStructSequence_UnnamedField

   Special value for a field name to leave it unnamed.

   在 3.9 版更改: The type was changed from "char *".

PyObject* PyStructSequence_New(PyTypeObject *type)
    *Return value: New reference.*

   Creates an instance of *type*, which must have been created with
   "PyStructSequence_NewType()".

PyObject* PyStructSequence_GetItem(PyObject *p, Py_ssize_t pos)
    *Return value: Borrowed reference.*

   Return the object at position *pos* in the struct sequence pointed
   to by *p*. No bounds checking is performed.

PyObject* PyStructSequence_GET_ITEM(PyObject *p, Py_ssize_t pos)
    *Return value: Borrowed reference.*

   Macro equivalent of "PyStructSequence_GetItem()".

void PyStructSequence_SetItem(PyObject *p, Py_ssize_t pos, PyObject *o)

   Sets the field at index *pos* of the struct sequence *p* to value
   *o*.  Like "PyTuple_SET_ITEM()", this should only be used to fill
   in brand new instances.

   注解:

     This function "steals" a reference to *o*.

void PyStructSequence_SET_ITEM(PyObject *p, Py_ssize_t *pos, PyObject *o)

   Macro equivalent of "PyStructSequence_SetItem()".

   注解:

     This function "steals" a reference to *o*.
